Using an organic EL element as a light source of a vehicle lamp has been recently reviewed. Unlike a light emitting diode (LED) that is similarly used as a light source, the organic EL element has a characteristic that a luminous flux maintenance factor largely decreases under a high temperature environment. This problem needs to be solved in order to prolong the lifetime of the organic EL element.
Japanese Patent Laid-Open Publication No. 2010-205714 discloses a method of suppressing the temperature rise of an organic EL element in a lighting device including the organic EL element by attaching a heat conductive film to the organic EL element.